Resposta :
[tex]\boxed{\begin{array}{l}\sf4NH_3+3O_2\longrightarrow 2N_2+6H_2O\\\sf\\\sf68~g~de~NH_3\longrightarrow56~g~de~N_2\\\sf45~g~de~NH_3\longrightarrow x\\\sf 68x=45\cdot56\\\sf x=\dfrac{45\cdot56}{68}\\\\\sf x=37,05~g~de~N_2\\\\\sf rendimento=\dfrac{massa~te\acute orica}{massa~real}\cdot100\\\\\sf rendimento=\dfrac{36}{37,05}\cdot100\\\\\sf rendimento=97,16\%\end{array}}[/tex]